Radio communication systems are used for transmitting information, speech or data, with the aid of electromagnetic waves over a radio interface, also called an air interface, between a sending and a receiving radio terminal. Radio communication systems can be subdivided into a core network and a Radio Access Network (RAN). User data and signaling data of a plurality of terminals is line-conducted over large distances in the core net. In addition, a connection to a fixed communication network can be implemented via the core network. In the radio access network, data received from the terminals is converted into a format suitable for transmission in the core network. Additionally, the form of data received by the core network is adapted to radio transmission and forwarded to the relevant radio terminal, within the send area of which the terminal involved is located.
Radio communication systems of the first and second generation are currently in use around the world and, because of the great demand for mobile communication, are coming up against the limits of their capacity. The emerging capacity problems are to be resolved by the third-generation radio communication systems. One of the third-generation radio communication systems which shows the greatest promise of success is the Universal Mobile Telecommunication System (UMTS) that was specified by the standardization body 3GPP (Third Generation Partnership Project) (see for example: B. Walke, Mobilfunknetze und ihre Protokolle [Mobile radio networks and their protocols], Volume 1, pp. 370–396, Teubner Verlag 2000).
In UMTS several 5-MHz-wide frequency channels are available within a 60-MHz band for transmission via the air interface. The various 5-MHz-wide frequency channels can here be assigned to different mobile radio operators. For each of the 5-MHz-wide frequency channels it is necessary, in accordance with the terms of UMTS allocation, to set up an independent infrastructure with a core network and a radio access network.
As is apparent from the press release from the regulatory authority for telecommunications and post, UMTS Infrastructure Sharing of 5 Jun. 2001, and from the Infrastructure Sharing paper (Thesenpapier Infrastruktur-Sharing), the shared use of land, masts, antennas, cables and combiners by several operators is permissible. Also covered by this is the shared use of a cabinet in which base stations, amplifiers and power supply are housed, as well as the use of logically split base stations and/or radio network controllers, providing it is ensured that each operator has independent control of its own logical unit.
S. Breyer et al., “UMTS node B architecture in a multi-standard environment”, Alcatel Telecommunications Review, 1st Quarter 2001, pages 50–54 discloses a multi-standard Node B which can process connections in accordance with the UMTS standard as well as in accordance with the GSM standard. The Node B has a common control unit and a common transmission unit for exchanging data with the relevant core network. Separate send and receive devices as well as signal processing devices are used for each standard for transmissions via the air interface.
U.S. Pat. No. 5,781,865 discloses a mobile radio system that allows a plurality of PCS operators to operate common antenna locations. A common bandpass filter and a common amplifier are provided here downstream of the respective antenna. The signals are assigned to the individual operators using a splitter.